1. Field of the Invention
The present invention relates to a liquid image forming apparatus, and more particularly, to a liquid image forming apparatus with a dipping-type developing unit in which part of a developing roller is dipped in a developer.
2. Description of the Related Art
Liquid image forming apparatuses such as color laser printers form an electrostatic latent image corresponding to a desired image by radiating light onto a photosensitive body, develop the electrostatic latent image with a developer in which powder-shaped toner is mixed with a liquid solvent, and print the developed electrostatic latent image onto paper.
FIG. 1 shows the structure of a conventional liquid image forming apparatus. The image forming apparatus shown in FIG. 1 includes a laser scanning unit (LSU) 30 to radiate light onto a photosensitive body 40 and form an electrostatic latent image on the photosensitive body 40, a plurality of developing units 10 to develop the electrostatic latent image with developers of predetermined colors, and a transfer unit 20 to transfer the developed image onto a paper S.
As shown in FIG. 2, the developing units 10 include a developing container 16 in which a developer supplied from a cartridge 15 is received, a developing roller 11 having a portion which is dipped in the developer of the developing container 16, which rotates and is opposite to the photosensitive body 40, and a depositing roller 12 which forms a depositing gap G between the depositing roller 12 and the developing roller 11 such that the developer is attached to the surface of the developing roller 11, and forms a potential difference between the depositing roller 12 and the developing roller 11 . The developing units 10 further include a metering roller 13 which regulates the developer stuck on the developing roller 11 within a predetermined range of thickness, an agitator 5 which agitates the developer in the developing container 16, and a cleaning roller 14 which cleans the surface of the developing roller 11. The cleaning roller 14 is formed of a sponge material, rotates in the same direction as the developing roller 11 while contacting the developing roller 11, and cleans toner particles of the undeveloped developer stuck on the developing roller 11.
However, in the image forming apparatus having the above structure, bubbles 17 are generated by the cleaning roller 14 in the developer while the electrostatic latent image formed on the photosensitive body 40 is developed by the developing units 10. That is, the cleaning roller 14 performs a cleaning operation while rotating in the same direction as the developing roller 11. In this case, the water level of the developer becomes uneven, as shown in FIG. 2. Then, part of the cleaning roller 14 is exposed to air, and thus the air passes through pores of the sponge. In addition, the air is passed to the outside by pressure where the cleaning roller 14 is pressed against the developing roller 11, and thus the cleaning roller 14 generates the bubbles 17 in the developer. Due to this problem, the bubbles 17 enter into the depositing gap G, prevent the toner from being uniformly attached to the developing roller 11, burst on the surface, scatter the developer, and contaminate peripheral devices.
Thus, a structure which can solve the problem caused by generation of the bubbles 17 is required.
Accordingly, it is an object of the present invention to provide a liquid image forming apparatus having an improved structure in which generation of bubbles in a developer of a developing unit is suppressed.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and/or other objects of the present invention are achieved by providing a liquid image forming apparatus including a photosensitive body; a laser scanning unit to radiate light onto the photosensitive body and form an electrostatic latent image on the photosensitive body; a developing unit to develop the electrostatic latent image with a developer having a color; a transfer unit to transfer the developed image onto a paper, wherein the developing unit includes a developing container in which the developer is received, a developing roller having a portion which is dipped in the developer in the developing container, the developing roller being opposite to the photosensitive body, a cleaning roller which cleans the developer remaining on the developing roller after the electrostatic latent image is developed, and a squeeze unit which squeezes the cleaning roller before the developing roller is cleaned, and eliminates air which is in the cleaning roller to an outside.